A display device includes: a display panel; a power management circuit configured to: perform a short detection operation with a first short detection condition during a start-up operation; supply first and second power supply voltages in the normal mode; and stop supplying the first and second power supply voltages in the low power mode; and a display driver configured to provide a first image signal in the normal mode and a second image signal for in the low power mode, the display driver comprising a power block configured to supply first and second standby power supply voltages in the low power mode, wherein, in a transition frame between the low power mode and the normal mode, the display driver provides the second image signal for the standby image to the display panel, and the power management circuit performs the short detection operation with a second short detection condition.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A display device comprising: a display panel configured to display a normal image in a normal mode and a standby image in a low power mode; a power management circuit configured to: perform a short detection operation with a first short detection condition during a start-up operation that activates a first power supply voltage and a second power supply voltage at power-on of the display device; supply the first power supply voltage and the second power supply voltage to the display panel in the normal mode; and stop the supply of the first power supply voltage and the second power supply voltage in the low power mode; and a display driver configured to provide a first image signal for the normal image to the display panel in the normal mode, and to provide a second image signal for the standby image to the display panel in the low power mode, the display driver comprising a power block configured to supply a first standby power supply voltage and a second standby power supply voltage to the display panel in the low power mode, wherein, in a transition frame between the low power mode and the normal mode, the display driver is configured to provide the second image signal for the standby image to the display panel, and the power management circuit performs the short detection operation with a second short detection condition different from the first short detection condition.
2. The display device of claim 1 , wherein the first short detection condition refers to a condition that a panel current flowing through the display panel is greater than a first reference current, and wherein the second short detection condition refers to a condition that the panel current is greater than a second reference current, the second reference current being greater than the first reference current.
3. The display device of claim 2 , wherein the second reference current is greater than the first reference current by a driving current flowing through the display panel for displaying the standby image.
4. The display device of claim 1 , wherein the display driver is configured to transfer a short detection condition setting pulse indicating the second short detection condition to the power management circuit to change a short detection condition of the power management circuit from the first short detection condition to the second short detection condition, in response to receiving a mode control signal to enter the low power mode, and wherein the display driver is configured to transfer the short detection condition setting pulse indicating the first short detection condition to the power management circuit to restore the short detection condition of the power management circuit to the first short detection condition, in response to receiving a mode control signal to transition from the low power mode to the normal mode.
5. The display device of claim 4 , wherein the short detection condition setting pulse is transferred through a single wire between the display driver and the power management circuit.
6. The display device of claim 1 , wherein the display panel is configured to display the standby image based on the second image signal provided from the display driver in the transition frame from the low power mode to the normal mode.
7. The display device of claim 1 , wherein a line through which the first power supply voltage is supplied from the power management circuit to the display panel and a line through which the second power supply voltage is supplied from the power management circuit to the display panel are in high impedance states in the low power mode.
8. The display device of claim 1 , wherein a line through which the first standby power supply voltage is supplied from the power block to the display panel and a line through which the second standby power supply voltage is supplied from the power block to the display panel are in high impedance states in the normal mode.
9. The display device of claim 1 , wherein the power management circuit is configured to, during the start-up operation, activate the first power supply voltage, and then activate the second power supply voltage, wherein the power management circuit is configured to perform the short detection operation from a starting point of the activation of the first power supply voltage to a starting point of the activation of the second power supply voltage, and wherein the power management circuit is configured to: determine whether the first short detection condition is satisfied according to a voltage level of the second power supply voltage during the short detection operation at the power-on; and determine whether the second short detection condition is satisfied according to the voltage level of the second power supply voltage during the short detection operation in the transition frame.
10. The display device of claim 1 , wherein the power management circuit comprises: a boosting converter configured to generate the first power supply voltage; an inverting converter configured to generate the second power supply voltage; a pull-down transistor connected to a line through which the second power supply voltage is supplied from the power management circuit to the display panel; a pull-down resistor connected between the pull-down transistor and a ground voltage; a comparator configured to compare the second power supply voltage with a short detection reference voltage; and a short control block configured to shut down the power management circuit in response to an output signal of the comparator.
11. The display device of claim 10 , wherein the pull-down transistor is turned on to pull down the second power supply voltage in response to performing the short detection operation.
12. The display device of claim 10 , wherein the short detection reference voltage has a first voltage level in response to performing the short detection operation with the first short detection condition, wherein the short detection reference voltage has a second voltage level in response to performing the short detection operation with the second short detection condition, and wherein the second voltage level is higher than the first voltage level.
13. The display device of claim 1 , wherein the low power mode is an always-on display (AOD) mode.
14. The display device of claim 1 , wherein the standby image is an always-on display (AOD) image comprising at least one of a time image, a date image and a weather image.
15. A method of operating a display device, the method comprising: performing, by a power management circuit, a start-up operation that activates a first power supply voltage and a second power supply voltage and a short detection operation with a first short detection condition at power-on of the display device; supplying, by the power management circuit, the first power supply voltage and the second power supply voltage to a display panel in a normal mode; providing, by a display driver, a first image signal for a normal image to the display panel in the normal mode such that the display panel displays the normal image in the normal mode; supplying, by the display driver, a first standby power supply voltage and a second standby power supply voltage to the display panel in a low power mode; providing, by the display driver, a second image signal for a standby image to the display panel in the low power mode such that the display panel displays the standby image in the low power mode; providing, by the display driver, the second image signal for the standby image to the display panel in a transition frame between the low power mode and the normal mode; and performing, by the power management circuit, the start-up operation and the short detection operation with a second short detection condition, the second short detection condition being different from the first short detection condition in the transition frame.
16. The method of claim 15 , wherein the first short detection condition refers to a condition that a panel current flowing through the display panel is greater than a first reference current, and wherein the second short detection condition refers to a condition that the panel current is greater than a second reference current the second reference current being greater than the first reference current.
17. The method of claim 16 , wherein the second reference current is greater than the first reference current by a driving current flowing through the display panel for displaying the standby image.
18. The method of claim 15 , wherein the display panel displays the standby image based on the second image signal provided from the display driver in the transition frame from the low power mode to the normal mode.
19. The method of claim 15 , wherein the low power mode is an always-on display (AOD) mode.
20. The method of claim 15 , wherein the standby image is an always-on display (AOD) image comprising at least one of a time image, a date image and a weather image.
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January 24, 2019
June 2, 2020
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